Once our own key-pair is created, we can begin to put into our public keyring database of all keys we have from some trusted third partly in order to be able to use his/her keys for future encryption and authentication
communication. To import Public Keys to your keyring, use the following command:

The above command will append all new keys to our keyring database and will update all already existing keys. It is important to note that GnuPG does not import keys that are not self-signed. In the above example
we import the Public Key file redhat2.asc from the company Red Hat Linux, downloadable from the Red Hat Internet site, into our keyring.

When you import keys into your public keyring database and are sure that trusted third party is really the person they claim, you can start signing his/her keys. Signing a key certifies that you know the owner of the keys.
To sign a key for the company RedHat that we have added on our keyring above, use the following command: